\begin{abstract}

In most of the cloud computing scenarios in today's world, a client and a
server engage in a contract where the server provides computation time to the
client in exchange of money. Such an exchange of money and computation results
is regulated by a trusted third party (a bank) that handles the payment
processing, and requires the client to trust the server that the results
returned are indeed correct.  It is well known that no possible deterministic
solution to facilitate a fair exchange of money and the results of the
computatin exists without involving a trusted third party. We propose a
practical solution to such a fair exchange problem in the limited situation
where the money is transferred in form of bitcoins and both the parties run
commercially available TPM chips. The trusted third party in such a case is the
hardware manufacturers for the TPM chips and the bitcoin network. We also
explore the ways for ensuring that the results returned by the server are
indeed correct.


\todo{remove this: \cite{nakamoto2012bitcoin}}
\end{abstract}
